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…making comparisons, resemblances resulting from convergence must be considered. Whales and bony fishes, for example, have similar body shapes for the same function—progression through water. Their internal features, however, are widely different. In this case, the convergence is evident because of the large number of characters that link whales to…

…appearance by a process termed convergence. An example is the convergence of the streamlined form in the bodies of squid, shark, seal, porpoise, penguin, and ichthyosaur, animals of diverse ancestry. Physiological processes and behaviour patterns may also exhibit analogous convergence. Egg-guarding behaviour in the cobra, the stickleback, the octopus, and…

Unrelated species living in similar physical environments often are shaped by natural selection to have comparable morphological, physiological, or life history characteristics; they are said to evolve convergently (see The Rodent That Acts Like a Hippo). Convergence is a common feature of evolution and…

…environments, a phenomenon known as convergent evolution. Structural similarities—streamlined shape, dorsal fins, tail fins, and flipper-like forelimbs and hindlimbs, for example—have evolved in such varied animal groups as the dolphins and porpoises, both of which are mammals; the extinct ichthyosaurs, which were reptiles; and both the bony and cartilaginous fishes.…

SIDEBAR

Although the animals that live in rainforests on different continents can differ significantly, the environments they live in are very similar. These environments, therefore, exert similar pressures on the evolution of the animals living in each. As a result, unrelated species may be similar in…

development in evolution

Convergence is often associated with similarity of function, as in the evolution of wings in birds, bats, and flies. The shark (a fish) and the dolphin (a mammal) are much alike in external morphology; their similarities are due to convergence, since they have evolved independently…

…led to numerous examples of convergence in the evolutionary history of eyes. The similarity in optical design of the eyes of fish and cephalopod mollusks, such as octopuses and squid, is perhaps the most well-known example, but it is only one of many. The same lens design is also found…

Among present-day species, convergent evolution has led to the development of similar traits among different falconiforms. For instance, in Australia, buzzards (Buteo) are absent, but certain large kites have evolved to fit this ecological niche. In South America the buzzardlike harpy eagle represents a climax of one line…

Such resemblances are examples of convergent evolution—a tendency for organisms to adapt in similar ways to similar habitats. Thus, there are marsupials that look remarkably like moles, shrews, squirrels, mice, dogs, and hyenas. Others are the ecological counterparts, less in structure than in habits, of cats, small bears, and rabbits.

…that these anatomical resemblances are convergent (the result of the same type of natural selection acting on unrelated organisms) and that the true relationships of hummingbirds and swifts lie with other groups, not with each other.

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